Printing a column

I am attempting to build a gear with a shaft on one side, see STL file.

The shaft is 10mm high with a 5mm hole in the end, the hole has squared off sides to provide grip on the motor shaft.

The print is OK until it reaches the bottom of the column hole at which point it reduces from 8mm to 6.3mm.

The Gcode file is also attached as it seems to be the translation from the STL to the Gcode that is the problem.

I am using Repetier and Slic3r software

Can anyone suggest corrections?

How big is the nozzle? 8-6.3 = 1.7 mm which means the wall will be 1.7/2 = 0.85 mm thick. That's a very thin wall, and the shear force will be trying to break the layer adhesion of that very thin wall. How much mechanical force will this thing have to withstand?

The very small size means the plastic will not cool and solidify before the nozzle dumps more liquid plastic on the previous layer. It's going to mushroom and look and fit like crap. You're going to have to print more than one (maybe 5) of these at a time if you want the print to come out half-way decent.

Edited 1 time(s). Last edit at 10/17/2020 03:47PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thank you for your response, I am going to show how little I know here by the following.

I am using a 0.4mm nozzle and 1.75mm PLA filament.

I do not understand where your math comes from, could you explain that more clearly so that I can make appropriate corrections to my Slic3r setup.

You have an 8mm diameter column with a 6.3 mm hole. That means the walls will be 0.85 mm thick. That's two lines from your 0.4 mm nozzle.
What is 5mm? what is 10mm high?
Have you told slic3r how big the nozzle is? And the line widths that you want?




Edited 1 time(s). Last edit at 10/18/2020 08:45PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Once again, thank you, the light has finally gone on.
I increased the diameter from 8 to 12 and let it overlap the gear teeth.
This seems to have eliminated my problems, another learning experience.
This gear is for a very low speed geared 3v DC motor driving a number of gear sets of various sizes in a Tellurion, i can adjust the length of the shaft to center the driving gear on the driven gear.
Cheers